X-ray film changer having a storage chamber with a wall which pivots as cassettes are fed thereto

ABSTRACT

Device moving X-ray film cassettes from supply, to exposure, to exposed positions in controlled time sequence as a series of Xray exposures are made.

[50] Field 250/65, 66,

[72] Inventors John W. Smit Rexdale; William R. Salt, Kleinburg,Ontario, Canada Appl. No. 673,625

[56] References Cited UNITED STATES PATENTS 3,015,028 12/1961 2,107,8252/1938 Humphreys 2,617,944 11/1952 Primary Examiner-James W. Lawrence[22] Filed Oct. 9, 1967 [45] Patented Feb. 2, 1971 [73] Assignee PickerX-Ray Mfg., Limited Assistant ExaminerC. E. Church Attorney-Watts,Hoffmann, Fisher & Heinke CASSETTES ARE FED THERETO 11 Claims, 11Drawing Figs.

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PATENTEU FEB 2mm 3.560.743 SHEET 1 OF 9 INVENTORS JOHN W. SMIT WiLLIAMR.SALT BY waits, .RSM w 1 ATTORNEYS.

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PATENTED FEB 2191: v $560,743

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SHEET 7 UF 9 INVENTORS. JOHN W.SMIT WILLIAM R. SALT B wamflowmmpsm n ATTORNEYS.

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SHEET 8 OF 9 INVENTORS. JOHN W. SMIT WILLIAM R.SALT

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X-RAY FILM CHANGER HAVING A STORAGE CHAMBER WITH A WALL WHICH PIVOTS ASCASSE'I'IES ARE FED TIIERETO CROSS REFERENCE TO RELATED APPLICATIONS Thefollowing pending application for US. Letters Pat. is cross referencedherein: application of Frank H. Umberg and Cecil K. Bridgeman, Ser. No.433,251, now Pat. No. 3,348,042 filed Feb. 10, 1965, and entitled FILMPACK.

BACKGROUND OF THE INVENTION This invention relates to roentgenograph andmore particularly to a film changer and methods of changing film fortaking a series of radiographs, especially in rapid sequence and inSUMMARY OF THE INVENTION The film changer of the present invention isadapted to handle film in individual cassettes or film holders. Thechanger automatically positions a cassette for exposure of'the film,transfers it after exposure, and moves a'successive cassette intoposition for the next radiograph. The preferred embodiment is especiallyadapted to handle vacuum cassettes of X- ray film of the type describedand claimed in the copending application of Frank H. Umberg, and CecilK. Bridgeman, Ser. No. 433,251, filed Feb. 10, 1965, entitled FILM PACK.As described in the said copending application, a sheet of X-ray film issandwiched between intensifier plates in an evacuated, light tight,plastic pouch. A lead barrier behind. the film in the cassette allowsthe cassettes to be used in a stack while the film in the top cassetteis exposed.

The film changer of the present invention is constructed so that thefilm can be exposed and changed with the changer oriented eitherhorizontally or vertically. As a result, two changers can be operated asa pair, so that radiographs of a patient can be taken from twodirections without moving the patient or the X-ray apparatus. Inaddition, the film changer is constructed so that the timed sequence andinterval between successive radiographs can be controlled by a cardprogrammer of other suitable input. This pennits the operation of thechanger to be coordinated with the automatic control of a syringe forinjecting dye into the circulatory system of the patient being X-rayed.

When the plastic evacuated cassettes described in the abovevreferencedcopending application, or similar but nonevacuated cassettes, are usedwith the apparatus of this invention, one modification as compared withthe disclosure of the referenced application is required. That is, sincethe cassettes here are presented in a stack with the top one of thatstack exposed, it is necessary that either each cassette contain a leadsheet to prevent exposure of any film below that cassette in the stack,or that alternate ones of the stack of cassettes contain lead sheetswith the remainder containing film and intensifying screens.

In that situation where two changers are used concurrently, the normalprocedure is to expose film alternately in one changer and then theother. Thus, if one changer is horizontal and the other vertical, firsta vertical exposure will be made and then a horizontal and so on.

As an example, when. a vertical exposure is being made, scatterradiation from that exposuremay partially expose a sheet of film in thehorizontal changer. Because of this scatter radiation problem where twochangers are used, it is desirable to provide a stack of cassettes inwhich ziltematc cassettes contain lead sheets and the remainingcassettes contain film and intensifier screens. Thus, as a verticalexposure is made, a lead sheet will be at the top of the pile in thehorizontal changer. After the vertical exposure is made, both theexposed vertical film and the lead in the horizontal changer are fed outof the exposure positions in the two changers. A cassette with a leadsheet then moves to the top of the pile in the vertical changer and acassette containing a. film and intensifier screens moves to the top ofthe pile in the horizontal changer.

The basic arrangement of the film changer utilizes a side-byside loadingand unloading mechanism. A stack of X-ray film cassettes is provided inthe loading mechanism and biased against an X-ray window. One-bycne thecassettes are automatically exposed, transferred in a controlled timesequence by a reciprocating feeding arm and power driven roller feed toan unloading station, and the stack is advanced to position a successivecassette for exposure.

One of the outstanding features of this invention is the utilization ofa substantial biasing force which presses a stack of unexposed cassettestoward the exposure station. This biasing force clamps the stack ofcassettes together with the top one of the stacks, when the stack isvertically disposed, in the exposed position and under substantiallybiasing force which compresses the intensifying screen and film togetherin tighter intimate contact than has heretofore been available in filmchangers. This better intimate contact. and therefore better resolutionof the image produced on the X-ray film, is ob tained even when theplastic cassette identified in the aboveidentified cross-referencedapplication is not evacuated.

The use of this substantial spring pressure produces yet anotheradvantage. This other advantage is that for any given space, because ofthe compactness of the vacuum cassette and the elimination of spring orotherclampiing means in each cassette, the cassettes are thinner andtherefore more films can be disposed in any given space.

A further important feature of the film changer is the automatic removalof biasing pressure against the stack of cassettes when each cassette istransferred]. The biasing force is then reestablished on the stackbefore the subsequent cassette is exposed to X-rays. This advances thenext cassette into the exposed position and assures the outstandingfilter-screen contact obtained with this device.

The release of pressure, coordinated with the movement of the feed amand the driven roller, produces an extremely short transfer time forchanging the cassette and film, which facilitates rapid sequenceradiographs at. speeds exceeding the change times previously obtainable.

Accordingly, it is an object of this invention to provide a novel andimproved film changer and method for rapidly and reliably positioningand transferring a series of film cassettes for exposure to X-rays.

Other objects, features and advantages of this invention will becomeapparent as the invention becomes better understood from thedetaileddescription that follows, when considered in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic perspectiveview showing two film changers constructed in accordance with thepresent invention, one oriented horizontally and the other vertically,and arranged adjacent each other to facilitate radiographing a patientin two directions without moving the patient;

FIG. 2 is a vertical, longitudinal, sectional view, on an enlargedscale, of the vertical film changer of FIG. 1, illustrating the internalconstruction and arrangement;

FIG. 3 is an elevational view, on an enlarged scale, of a control andfeeding mechanism assembly as viewed from the rear side of the changer;

FIG. 4 is a top plan view of the assembly of FIG. 3;

FIG. 5 is an end elevational view of the assembly of FIGS. 3 and 4;

FIG. 6 is a side elevational and sectioned view of the a sembly of FIGS.3 and 4 as seen from the planes indicated by the line 6-6 of FIG. 4;

FIG. 7 is a sectional view of the mechanism assembly of FIGS. 3 and 4 asseen from the planes indicated by the line 7-7 of FIG. 4;

FIG. 8 is a front elevational view of the unloading chamber assemblywith parts removed;

FIG. 9 is a side elevational view of the tilting mechanism of theunloading chamber assembly;

FIG. 10 is a side elevational view similar to FIG. 9, with parts insection and other parts removed;

FIG. II is a partial sectional view of the loading chamber assembly,illustrating the manner in which a film a cassette is fed to theunloading chamber assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Arrangement The generalappearance and overall arrangement of a film changer constructed inaccordance with the present invention for exposing and changingsuccessive film cassettes is shown in FIG. 1 of the drawings. Forillustrative purposes, two changers indicated generally at and 22 areshown. The construction is such that the film changers can be orientedeither vertically as shown at 20, or horizontally as shown at 22. Ifdesired, they can be located adjacent each other, as shown in FIG. 1, toprovide for their concurrent use with two X-ray tubes 24, 26 for takingradiographs of a patient from two directions.

The mechanism of each film changer is contained within a housing 30 ofsuitable metal sheet with reinforcing frame members and which can besupported on a suitable base 32. One surface 34 of the housing 36 isprovided with an opening covered by an X-ray transparent plate 35,defining an X-ray station 36 where the patient is positioned. Twoside-by-side doors 37, 38 are provided in each 5 side of the housing 30.The door 37 and its counterpart on the opposite side of the housingprovide access to a loading chamber beneath the plate which receives asupply of X-ray film cassettes to be exposed in succession. The door 38and its counterpart on the opposite side of the housing open into anunloading chamber that is to one side of the loading chamber when thechanger is horizontal, and that is beneath the loading chamber when thechanger is vertical. Cassettes with exposed film are removed from thefilm changer through the doors 38.

The internal construction and arrangement of the film changer 22 isshown in FIG. 2 of the drawings. The film changer comprises a loadingchamber assembly 40 beneath the X-ray station 36, and an unloadingchamber assembly 42 to one side thereof in the horizontal orientationshown. The loading and unloading chambers are separated by a transferroller 44 adjacent the top of the housing 30.

The loading chamber assembly 40 holds a supply of film cassettes 46which are successively exposed to X-rays and transferred to theunloading chamber assembly 42. The top of the loading chamber 40includes an opening 48 in the housing 30 for interchangeable X-ray gridsor plates. The opening is covered by the plate 35. A bottom locatingplate 50 also covers the opening 48, within the loading chamber assembly46 and spaced from the top cover plate 35. The bottom plate 50 is X-raytransparent and acts as a pressure plate at the X- ray station againstwhich the cassettes 46 are urged. This plate locates the X-ray filmbeing exposed in a desired plane close to the patient. Internalsidewalls 52, two of which are shown at 52a, 52b in FIG. 2, provide ahousing that aligns and guides the cassettes 46 in proper locationbeneath the bottom locating plate 50. A loading platform 54 completesthe housing for the cassettes 46 and is movable within the sidewalls 52toward and away from the bottom locating plate 50. The loading platform54 urges the cassettes 46 against the bottom plate 50 and movessuccessive cassettes into proper location for exposure.

A control mechanism assembly indicated generally by the referencenumeral 55 is located within the loading chamber assembly 40, beneaththe stack of cassettes 46 and loading platform 54. The control mechanismassembly 55 controls the feeding of cassettes 46 from the loadingchamber assembly 40 to the unloading chamber assembly 42 and, inaddition, controls the overall sequence of the film changer operation. Atube 56, reciprocably movable by the mechanism assembly 55, extends fromthe assembly 55 and is attached to the loading platform 54. Themechanism assembly 55 moves the tube 56 and loading platform 54 in acontrolled manner to advance and bias cassettes 46 against the bottomplate 50. It also withdraws the tube 56 and platform 54 slightly toremove the biasing force when an exposed cassette is transferred intothe unloading chamber assembly. A feed arm indicated generally at 58extends from the control mechanism assembly 55 to one side of the stackof the cassettes 46, adjacent one end of the housing 30. A distal end ofthe feed arm 58 is connected with a feed finger 60 reciprocable betweenupper and lower guide plates 61, 62 in the plane of a cassette 46adjacent the bottom plate 50. Oscillation of the feed arm 58reciprocates the feed fingers 60 within the upper and lower guide plates6!, 62, and pushes an exposed cassette 46 toward the feed roller 44 totransfer the cassette. The control mechanism assembly 55 is described inmore detail subsequently.

A shutter assembly 64, shown in FIG. 2 and in more detail in FIG. 10,cooperates with a slot opening 66, providing a passageway for cassettes46 from the loading chamber assembly 40 to the transfer roller 44. Theshutter assembly 64 includes a shutter plate 68 slidably retained by aplate 69 against the outside surface of the inner transverse sidewall52!) that forms a housing for the cassettes 46. A bracket 70 is weldedto the shutter plate 68 and receives the end of a flexible cable 71.Movement of the shutter plate 68 to selectively open or close theshutter openings 66 is accomplished through the cable 71 by a shutteractuating mechanism 72, shown in FIG. 2 and associated with theunloading chamber assembly 42. In a manner that will be described inmore detail below, the shutter plate 68 is opened after film cassettes46 are loaded into the loading chamber assembly 40 so that the cassettesmay be transferred to the unloading chamber assembly 42 duringoperation.

The film cassette transfer roller 44 is located just outside of thehousing for the cassettes 46, formed by the walls 52, and is parallel toand at the level of the shutter opening 66. Thus, the roller 44 extendstransversely across the housing 30, and receives cassettes 46 as theyare pushed through the shutter opening 66 by the feed arm 58, in amanner illustrated in FIG. 11. The roller 44 is driven by an electricmotor 75 (FIG. 2) through a belt 76 connected between a motor pulley 77and a roller pulley 78. During operation, the roller 44 is constantlydriven by the motor 75 in a clockwise direction as show shown in FIGS. 2and 11. A hold down roller 18 is spaced from and extends a parallel tothe roller 44 so that a cassette 46 passing through the shutter aperture66 can pass between the roller 44 and the hold down roller 80. The holddown roller 80 is supported in side brackets 82 pivoted at 83.Compression springs 84 carried by each bracket 82 push against the innersurface of the housing 30, biasing the hold down roller 80 toward thetransfer roller 44 and urging cassettes 46 into frictional engagementwith the transfer roller 44 when they are being transferred to theunloading chamber assembly. As best shown in FIG. 2, the end brackets 82position the hold down roller 80 initially spaced from the transferroller 44 a distance sufiicient to receive a cassette 46 when thecassette is moved through the shutter aperture 66.

The unloading chamber assembly 42 on the opposite side of the transferroller 44 from the loading chamber assembly 40 receives exposed filmcassettes 46 as they are exposed and transferred during operation. Theunloading chamber assembly 42 includes an upper receiving chamber 86into which the cassettes 46 are delivered and a lower tilting mechanism87 that changes the configuration of the chamber 86 when the filmchanger is oriented vertically.

The chamber 86 is formed by the sidewalls of the housing 30, one ofwhich is shown at 88 in FIG. 2, and (in the orientation of FIG. 2) by atop wall 89, a left sidewall 10, a right sidewall 91, and a lower wallformed by a platfonn 92 connected with the tilting mechanism 87. Theplatform 92 is shown in a tilted position to show the associatedmechanism beneath the platform. When the changer is used horizontally,as illustrated in FIG. 2, the platform is maintained in the positionshown in phantom. Preferably, the walls 89, 90 and 91 are constructed ofsound deadening material to minimize noise from the transfer ofcassettes into the unloading chamber assembly. A deflector 93 formed ofa strip of spring metal is attached to the top wall 89 and curved tointersect the path in which cassettes move from the transfer roller 44into the chamber 86. The deflector 93 directs the cassettes toward thereceiving platform 92.

When the film changer 22 is oriented vertically, as illustrated by thechanger 20 in F1G. 1, wall 91 forms the lower wall of the chamber 86.The wall 91 is formed of three flat segments 91a, 91b, 91c angularlyrelated to each other and to the receiving platform 92 so that when theplatform 92 is tilted as shown is full line in FIG. 2 and progressivelymoved to the position shown in phantom, the wall segments will beapproximately right angles to the platform 92. With this construction,when the changer is oriented vertically, cassettes received in thechamber 88 will be supported by the wall segments 91a, b, c and rest inan upright but slightly inclined position against the tilting platform92. During operation, the platform 92 is pivoted from an initialinclined position shown in solid line in MG. 2 to a final verticalposition shown in phantom in FIG. 2 as successive cassettes are receivedin the chamber 86. The receiving platform 92 is pivoted by the tiltingmechanism 87 in a manner that will be described, to assure a orderlyarrangement of cassettes in a generally vertical position when thechanger is vertical.

Control Mechanism Assembly The construction of the control mechanismassembly 55' is best shown in 3 to 7 of the drawings. Spaced parallelangle members 100, 101 (F1114) anchor spaced parallel supporting plates102, 103 to the frame work of the housing 30 of the film changer.Various drive, cam and pivot shafts forming the mechanism assembly 55are joumaled in the spaced supporting plates 102, 103.

A driven sprocket 104 receives power through a chain 105 from a powerdrive and clutch mechanism (not shown). The driven sprocket 104 and areducer sprocket 106 are supported for rotation by a sprocket shaft 107supported by plates 102, 103. Power from the sprocket 104 is transmittedby the reducer sprocket 106 through a chain 108 to a cam shaft drivesprocket 110. An idler sprocket 111 provides adjustment to maintain thechain 108 under tension.

The cam shaft drive sprocket 110 is keyed to a cam shaft 114 extendingthrough the supporting plates 102, 103 and journaled for rotation in theplates. A feed cam 116 for operating the feed arm 58, and a pressurerelease cam 118 for operating the loading platform 54 are secured to thecam shaft 14 between the spaced supporting plates 102, 103. Four controlcams 120, 121, 122, 123 are secured to the cam shaft 114 to the outsideof the plate 102. These four cams control four associated microswitchesMSl, M82, MS3, M54, which control the operation of the film changer.

The feed arm 58 operated by the feed earn 116 is comprised of twoelongated feed bars 126, 127 extending parallel to each other from thecontrol mechanism assembly 55 to a position adjacent the upper and lowerguide plates 61, 62, as shown in 1'16. 2. The two feed bars 126, 127 arefixed to a pivot shaft 128 journaled in the supporting plate 102, 103. Across pin 130 extends through the upper end of each of the feed bars126, 127 and engages the feed finger 60 shown in FIGS. 2, 3, and 10. Theopposite ends of the feed bars 126 are connected by a follower shaft 132that journals a cam follower 133, which follows feed cam 116.

A feed bar return mechanism 134 (FIG. 4) biases the feed bars 126, 127to a position where the feed finger 60 is withdrawn, as shown in FIG. 2.The return mechanism 134 includes a cross bar 135 extending through bothfeed bars 126, 127 just beneath the pivot shaft 126 1211. A link 136 ispivotally secured to each opposite end of the cross bar 135. Each passesthrough a bracket 137 extending from opposite sides of the mechanismassembly 55. A portion of each link 136 that extends through therespective bracket 137 is sur rounded by a compression spring 138 thatis compressed between the bracket 137 and a flange 139 at the end ofeach link 136. The springs 138 are further compressed when the feed cam116 pivots the feed arm 58 to advance a film cassette to the transferroller 44. As the feed cam 116 continues to rotate, the compressionsprings 138 bias the feed arm 58 so that the follower 133 continuecontinues to follow the feed cam and at the same time pivot the feed armto a withdrawn position.

From the above construction, it will be apparent that rotation of thefeed cam 116 rocks the two feed bars 126, 127 comprising the feed arm 58to cause the feed finger 60 to reciprocate back and forth within theupper and lower guide plates 61, 62.

A power input sprocket 140 carried by the control mechanism assembly 55is provided to retract the loading platform assembly 54 when driventhrough. a chain 141 by a plate loading motor (not shown). The sprocket140 drives a sprocket shaft 143 to which a chain supply sprocket 144 isfixed between the spaced supporting plates 102, 103. One end ofa chainlength 146 (FIG. 7) is secured to the chain supply sprocket 144, and thechain is wrapped around a portion of the sprocket periphery. Theopposite end of the chain 146 is secured to the movable tube 56 thatforms part of the loading platform assembly 54.

The tube 56 is slidable in a mounting sleeve 150 that is secured betweenthe spaced supporting plate 102, 103 and that encircles the tube 148near the upper end. A fixed tube guide 152 is fixed near the base of thecontrol mechanism assembly 55 and slidably engages the inner surface ofthe movable tube 56 so that the tube telescopes around the guide 152. Aninner tubular member 154 extends from the fixed tube guide 152concentrically within the movable tube 36 and is shorter in length. Thechain 146 is fastened by a connecting rod 156 within the tube 56 to theupper end adjacent the loading platform 54. The chain 146 extendsthrough a central opening 158 in the fixed tube guide 152 and extendsthrough the inner tubular member 154. A coil spring 159 encircles theinner tubular member 154 and extends between the fixed tube guide 152and a top plate 160 of the movable tube 148. The spring 159 biases themovable tube 56 away from the fixed tube guide 152 so that the tubetends to extend from the control mechanism assembly 55 in a directiontoward the plates 49 and 50 of the loading chamber assembly.

The chain 146 is entrained about a fixed sprocket beneath the fixed tubeguide 152, and about a floating sprocket 163 rotatably supported by astud shaft 162 on an arm 164, which is supported at one end by a pivotshaft 165. A brake drum 168 is secured to the floating sprocket. 163 forrotation with the sprocket about the stud shaft 162. The distal end ofthe pivoted arm 164 is biased against a stop 169 by a compression spring170.

A second arm 172 is pivoted midway between its ends on the pivot shaft165. The end of the second arm 172 adjacent the brake drum 168 supportsa brake pad 173 that prevents rotation of the brake drum 168 andfloating sprocket 163 when the pad is biased against the drum. A camfollower 176 is rotatably secured to the opposite end of the secondpivoted arm 172 and follows the pressure release cam 118. The camfollower 176 is biased against the cam 118 by a tension spring 178secured by pins 179 and 180 connected to the arm 172 and supportingplate 103, respectively.

When the cam 118 is rotated counterclockwise to where the lobe of thecam pivots the arm 172 in a counterclockwise direction as shown in FIG.7, the brake pad 173 presses against the brake drum 168 preventing;rotation of the brake drum 168 and floating sprocket 163. The cam 118further pivots the arm 172 against the biasing spring 170. exertingtension on the chain length 146 connected to the movable tube 56.Movement of the arm I72 pulls on the chain 146 and draws the movabletube 56 and loading platform 54 away from the top and bottom plates 35,50 of the loading chamber assembly. This movement is against the biasingforce of the spring 159 and the magnitude of the movement is small. Itis sufficient, however. to relieve the pressure forcing the cassettesagainst the bottom plate 50 of the loading chamber assembly so that thefeed finger 60 can easily push a cassette 46 through the shutter opening66 to the transfer roller 44. The

' lobe on the cam 118 is long enough to maintain the arm 172 pivotedlong enough to afford time for a cassette to be removed from the loadingchamber assembly by the transfer roller 44. Upon further rotation of thecam, the spring 178 will bias the arm 172 in a clockwise direction,removing the brake pad 173 from the brake drum 168. As a result, thechain 146 is movable and the spring 159 within the movable tube 56 isfree to bias the tube 56 and loading platform 54 in a direction towardthe top plate 35 and bottom plate 50 of the loading chamber assembly.This biasing of the spring 159 and the ability of the movable tube 56 toslide in the mounting sleeve 150 forces the remaining cassettes 46toward the bottom plate 50 where the next in the stack of cassettes isin a position to be exposed and then transferred to the unloadingchamber assembly.

Tilting Mechanism of the Unloading Assembly The tilting mechanism 87associated with the tilting platform 92 is best illustrated in FIGS. 8to of the drawings. As already mentioned, the platform 92 is tilted tochange its position during operation of the film changer when thechanger is in a vertical orientation. The purpose of varying the angleat which the platform 92 extends is to assure an orderly arrangementofexposed film cassettes at the receiving station. The platform 92 ispositioned at an angle as shown in FIG. 9 when the chamber 86 isrelatively empty, and is gradually moved to a vertical position ascassettes are received in the chamber 86. The cassettes'each rest with alower edge along the segmented wall 91 and lean against the inclinedplatform 92. As the platform 92 moves to a vertical position, thecassettes move with it by gravity along the supporting wall 91 toprovide additional space for subsequently received cassettes.

The platform 92 is secure secured within the unloading chamber assembly42 by pivot pins 181 on opposite sides and at one end of the platform92. The pivot pins are supported in spaced bracket plates 182 secured tothe housing. A peripheral flange 184 surround the platform 92 andextends to the rear of the platform. A tension spring 185 extend extendsbetween the platform 92 to the frame of the housing, biasing theplatform to a vertical position in the orientation of FIG. 9.

A first cam plate 188 and a second cam plate 189 are connected with theplatform'92 and extend generally perpendicular to the plane of theplatform. The first cam plate 188 is used to move the platform 92 to ainclined or tilted position as 7 shown in FIG. 9. The second cam plate189 controls the movement of the platform 92 back to a perpendicularposition as shown in solid line in FIG. 10 of the drawings.

As best shown in FIG. 9, the first cam plate 188 is pivotally secured toa support plate 192 extending to the rear and perpendicular to theplatfonn 92. The cam plate 188 is pivoted about a stud shaft 193 forlimited movement as provided by a short slot 194 in the support plate192. A pin 195 extending from the cam plate- 188 passes through the slot194. A tension spring 196 biases the cam plate 188 to the position shownin FIG. 9. A cam surface 197 of the cam plate 188 engages a cam follower199 on a first movable carriage 200 that is reciprocated up and down inthe orientation of FIG. 9 a by a screw 202 and guided by a rod 203. Whenthe carriage 200 is driven by the screw 202 from its lower position toits upper position, the follower 199 acts against the cam surface 197 totilt the platform 92 from the phantom position of FIG. 9 to the solidline position. When the carriage 200 reaches the upper limit of itstravel, the follower 199 leaves the cam surface 197 of the first camplate 188. and the platform 92, insofar as the carriage 200 isconcerned. is free to pivot from the tilted position back to thevertical position. However. it is limited by the second cam plate 189.

The second cam plate 189 is pivoted at an upper end in the orientationof the FIGS. 8 to 10 on a pivot 206. An opposite end of the second camplate 189 is connected to a plate 297 on the platform 92, by a slide pin208 that rides in an elongated slot 209 of the plate 207. A cam surface211 best shown in FIG. 10 of the drawings cooperates with the camfollower 212 of the second movable carriage 213 that is freely siidablevertically in the orientation of FIG. 10 along three supporting rods 214(see FIG. 8). The vertical position of the cam follower determines theangular position of the platform 92. Due to the contour of the camsurface 211, movement of the second s carriage 213 from a lower positionto an upper position allows the platform 92 to progressively pivot aboutthe mounting pivot pin 181 from an inclined position as shown in phantomin FIG. 10 to a vertical position as shown in full line.

Movement of the second carriage 213 from a lower position to an upperposition FIGS. 3 the orientation of FIGS. 8 to It is accomplished bypulleys 221 and 222, and a cable 223, as best shown in FIG. 8. Thepulley 221 is supported by a bracket 224 on a frame member 225 of thefilm changer. The pulley 222 is secured for rotation on the top of thesecond carriage 213 by a bracket 226. One end 2230 of the cable 223 issecured to the first carriage 200. The cable loops about both pulleys221 and 222 and extends from pulley 222, as indicated at 22311 to theloading platform 54 of the loading chamber as sembly 40. While theattachment of the cable portion 223b to the loading platform 54 is notshow, it will be understood that it is secured so that the movement ofthe loading platform 5d toward the bottom plates 50 at the X-ray stationas film cassettes are exposed and transferred, will pull on the cable223 and effectively shorten it with respect to the tilting mechanism 87.

As best shown in FIG. 10, with the second carriage 213 and pulley 222 ina upper position in the orientation as shown, the cam follower 212 andcam plate 189 have allowed the platform 92 to be returned to a verticalposition by the spring 185. With the second carriage 213 in a lowerposition as indicated in phantom, the cam follower 212 and cam plate 189hold the platform 92 in a tilted or inclined position.

From FIGS. 8 to 10 and the above description, it will be un derstoodthat movement of the first carriage 200 from the lower position of FIG.8 to the upper position will cause the platform 92 to be inclined to thefull line position of FIG. 9 and will effectively lengthen the cable 223to allow the second carriage 213 to slide along the supporting rods 214to a lower position under the influence gravity. While the firstcarriage 200 remains in its upper position, the loading platform 54 isgradually moved toward bottom plate 50 at the X-ray station assuccessive film cassettes 46 are exposed and transferred to theunloading chamber assembly. This progressively decreases the effectivelength of the cable 223 with respect to the tilting mechanism 87, andraises the second carriage 213 along the supporting rods 214.

As shown in FIGS. 8 and 9, the drive screw 202 for the first carriage200 is driven by a chain sprocket 230. The sprocket 230 is driven ineither of two desired directions by a chain and electric motor (notshown). The motor is reversible and its operation is controlled by thetwo pairs of doors 3'7, 38 of the housing 30. When two doors 37, 38 oneither side of the housing are opened to unload the cassettes from theunloading chamber assembly and to reload the loading chamber assembly,the sprocket 230 is driven to move the first carriage 200 from the upperposition to the lower position where it is shown in FIGS. 8 and 9. Thismovement of the carriage 200 pulls with it the cable 223 and resets theloading platform 54, pulling it away from the bottom plate 50 againstthe biasing force of the compression spring 159 within the movable tube148. Thus, with the changer vertical and the tilting mechanismoperating, it is not necessary to reset the loading platform with tilthe sprocket Mil and plate loading motor. although the chain must berewound about the sprocket. either by the motor or other suitable means.Alternatively. the movement of the carriage 20% can merely take upslaclt tn the cable 223 if the loading platform is reset by rotation ofthe sprocket M of the control mechanism assembly After cassettes as areplaced in the loading chamber d ll, the loading chamber door 37 isclosed. Closing the door 37 on either side of the housing operates thedrive motor for the sprocket 238 in the opposite direction so that thesprocket 23b and the screw 2lll2 drive the carriage Zllll to the upperposition. The drive for sprocket 225i is stopped by limit switches LSland LS2 whenever the carriage 200 reaches an upper or lower position.

A plunger operator 235 is secured to the frame of the film changer atthe upper end of the travel of the carriage 2048. See FIGS. 2 and 9. Aplunger rod 236 is biased by a spring Zdll to extend from the plungeroperator and is moved upward in the orientation of FIG. 9 and to theleft in the orientation of FIG. 2 by the carriage Zill). Movement of therod 236 pivots an arm 237 about a supporting pivot pin 23%. This slidesa wire 239 within the cable 7i to slide the connected shutter plate asin a direction that uncovers the slot opening as so that film cassettescan be transferred from the loading chamber as sembly to the unloadingchamber assembly. When the carriage am is moved from upper position to alower position after the cassettes 46 have been transferred to theunloading chamber assembly, the spring return 240 pivots the arm 237 andcloses the opening 66 by moving the shutter plate 68 over the opening.The shutter plate 68 assures that the cassette nearest the bottom plate50 will not slide through the opening 66 during loading before theloading platform applies pressure to the cassettes. Once the loading andunloading doors 37, 38 are closed and the cassettes ll) are pressedbetween the loading platform 54 and the bottom plate 50, the shutterplate 68 can be withdrawn, as it is when the carriage 2% moves from theupper position to the lower position.

Operation The four microswitches M31, 2, 3, 4 in part control thesequence of operation of the film changer. The switch M53 controls theexposure of the film cassettes by controlling the operation of anassociated X-ray tube. Switch M84 actuates a clutch-brake unit on thepower input to the sprocket 104. Switch MSl is a safety switch, andswitch M52 controls a backup timer that terminates the X-ray exposure ifit is not al ready terminated when the next cycle of the film changerbegins. This protects against an operator setting an exposure time on anassociated exposure control mechanism which is longer than the frequencyof cassette movement as controlled by a preselected program.

The power input to the chain 105 and sprocket d of the operatingmechanism assembly 55 is under the control of a suitable clutch andbrake so that rotation and power input to the operating mechanismassembly can be controlled. A cycle of operation occurs each time thecam shaft 114 rotates through 360 degrees. During this rotation, a filmcassette 46 is exposed to X-rays to produce a radiograph, is transferredto the unloading chamber assembly 42, and is replaced by a subsequentcassette. The external drive for the sprocket 104 is periodicallyenergized by an external control, for example, by a suitable program asmight be provided by a punched card indicating the number of radiographsto be taken and time delay between successive radiographs. The programcan also control the exposure time and the injection of dye into thepatient.

During each cycle when the cam shaft 114 is rotated, the loadingplatform 54 biasing the cassettes 46 against the bottom plate 5% ismoved a slight distance away from the bottom plate Ell by the pressurerelease cam i118 to remove the clamping pressure holding the cassettesin firm position. The feed arm 58 is then oscillated by the feed cam 116and the cassette 36 adjacent the bottom plate 50 of the housing 30 ismoved by the feed finger so through the shutter opening 66. Thecontinuously rotating transfer roller 44 engages the cassette which llllis forced into frictional engagement with the transfer roller by thehold down roller Rotation ol the transfer roller l -i car ties thecassette into the unloading chamber 4:2 where it is deflected by thedeflector spring ntl received on the unloading platform )2. The feed armthen oscillates back to its original position and the pressure releasecam llllli releases the loading platform 54 to push successive cassettesagainst the bottom plate Eli and force the film into tight intimatecontact with the associated intensifying screens.

At this time, the cam i252 actuates. the microswitch M83, which iselectrically associated with a circuit controlling the X-ray tube.Actuation of the switch lvlSil initiates exposure of the X-ray filmcassette positioned against the bottom plate S ll of the film changer.Rotation of the cam shaft llld is stopped by the actuation ofmicroswitch MS lby the cam i743.

With the film changer oriented horizontally, the shutter opening 66 neednot be closed by the shutter plate as. in addition, the tiltingmechanism 87 need not be operated.

When the film changer is oriented vertically, the tilting mechanism 87is operated to control the tilting platform 92 in the unloading chamberassembly l2. Considering the operation after one load of cassettes hasbeen exposed and transferred to the unloading chamber assembly, theopening of a door 37 and a door 38 to the loading and unloading chambersactuates switches that energize a drive motor connected with thesprocket 23b to run the carriage Zlllll to its lower position. Thiscloses the shutter plate as, retracts the loading platform 54 from thebottom plate Ell to provide space for additional cassettes in theloading chamber assembly. Cassettes are unloaded from the unloadingchamber assembly and new cassettes are placed in the loading chamber.

Closing of the loading door 37 energizes the motor driving sprocket 23bin an opposite direction, running the carriage Zllil to the upperposition. This moves the unloading platform 92 to an inclined position,increases the effective length of the cable 223 so that the carriage 2K3moves to a lower position, and moves the shutter plate 68 to an openposition. As cassettes are successively exposed and transferred in themanner previously described, the effective length of the cable 223 isdecreased, raising the carriage 2i? from its lower position toward anupper position. The inclined platform 92 is progressively returned to avertical position as successive cassettes are fed into the unloadingchamber 86.

While a preferred construction and mode of operation of the film changerof this invention has been described in detail, it will be understoodthat various modifications or alternations may be made therein withoutdeparting from the spirit or scope of the invention, as set forth in theappended claims.

We claim:

1. A film changer for use in taking a series of radiographs, said filmchanger comprising:

a. structure defining an X-ray station including means to locate acassette containing film at the X-ray station for exposure to X-rays;

b. a film cassette supply and transfer mechanism for changing film atthe X-ray station, including:

i. means supporting a plurality of film cassettes for movement to theX-ray station;

ii. means applying a force to bias the cassettes toward the X- raystation during exposure of the film to X-rays;

iii. means to temporarily relieve the force biasing the eassettes towardthe X-ray station; and

iv. means to move a cassette at least partially from the X-ray stationwhile the force biasing the cassettes is temporarily relieved,

c. structure defining a station for receiving cassettes transferred fromthe X-ray station, including a pivotal wall for supporting cassettestransferred to the receiving station; and

d. means to progressively pivot said wall as cassettes are transferredto the receiving station.

2. A film changer as defined in claim. 1 including a movable carriage atthe receiving station, means connecting the movable carriage and thepivoted wall so movement of the carriage controls pHOIlllg of the wall.and a connection between the film cassette supply and transfer mechamsmand the carriage so that the carriage IS moved as cassettes aretransferred from and supplied to the X-ray station.

3. A film changer as defined in claim 2 including another carriage.means to drive the said carriage independently of the first carriage topivot the wall and to move the means supporting the film cassettes awayfrom the X-ray station when the film changer is reloaded.

4. In a method of feeding a series of film cassettes to an X- raystation, and thence to a receiving station, the steps comprising:

a. applying a force to a plurality of cassettes to urge the plu ralitytoward an X-ray station;

b. exposing film in one cassette of the plurality to X-rays at the X-raystation while applying said force;

c. relieving the force urging the plurality of cassettes toward theX-ray station after the film has been exposed;

(1. while the force is relieved removing the cassette with the exposedfilm from the X-ray station by initially pushing it from an initialposition at the X-ray station in a generally vertical, downward,direction and then engaging it and conveying it from the X-ray stationto a receiving station;

e. applying another force to move the remaining cassettes of the stacktoward the X-ray station;

f. receiving the cassette in a generally upright position and supportingit against an upright support; and

g. progressively changing the angle at which the upright support isoriented as successive cassettes are received.

5. A film changer for use in taking a series of radiographs, said filmchanger comprising:

a. structure defining an X-ray station at which film cassettes areexposed to X-rays;

b. means to supply cassettes to the X-ray station;

c. transfer means to move exposed cassettes from the X-ray station;

(1. a receiving station for receiving exposed cassettes transferred fromthe X-ray station, said receiving station including a pivotally movablewall member; and

e. means to progressively change the angle of the wall member ascassettes are transferred to the receiving station.

6. A film changer as set forth in claim 5 wherein the means toprogressively change the angle of the wall member as cassettes aretransferred is controlled by the means to supply cassettes to the X-raystation.

7. A film changer as set forth in claim 6 including first and second camplates extending from the wall member in planes that intersect thepivotal axis of the wall, first and second carriages movable relative tothe pivot axis, each along a plane of one of the cam plates, at firstcam follower on the first carriage engageable with the first cam plate,a second cam follower on the second carriage engageable with the secondplate, means to independently drive the said first carriage to move thefirst cam follower along the first cam to pivot the wall member from afirst position to a second position, a spring biasing said wall memberfrom said second position toward said first position, and meansassociated with the cassette supply means to control movement of saidsecond carriage and second cam follower progressively along the secondcam as cassettes are transferred from the X-ray station to the receivingstation to allow the wall member to return to the first position.

8. A film changer as set forth in claim 7 including a movable shutterbetween the X-ray station and the receiving station, and means actuatedby the first carriage when it moves to tilt the wall member, to open theshutter and permit film cassettes to be transferred.

9. A film changer as set forth in claim 6 including a movable carriagereciprocable to control pivoting of the wall member.

10. In a method of transferring a series of film cassettes in agenerally upright orientation from an X-ray station to a receivingstation the steps comprising:

a. moving a series of cassettes one after the other from an upperlocation at an X-ray station to a lower location away from the X raystation along a ilredetermined path;

b. receiving the cassettes at t e lower location in a generally uprightposition;

c. maintaining the cassettes supported generally upright with a pivotedwall oriented generally upright; and

d. pivoting the wall from an initial inclined position to a positionmore toward the vertical as cassettes are moved from the upper locationto the lower location.

I l. The method of claim 10 wherein the wall is pivoted each time asuccessive cassette is transferred to provide an enlarged zone in whichto accommodate additional cassettes.

1. A film changer for use in taking a series of radiographs, said filmchanger comprising: a. structure defining an X-ray station includingmeans to locate a cassette containing film at the X-ray station forexposure to X-rays; b. a film cassette supply and transfer mechanism forchanging film at the X-ray station, including: i. means supporting aplurality of film cassettes for movement to the X-ray station; ii. meansapplying a force to bias the cassettes toward the Xray station duringexposure of the film to X-rays; iii. means to temporarily relieve theforce biasing the cassettes toward the X-ray station; and iv. means tomove a cassette at least partially from the X-ray station while theforce biasing the cassettes is temporarily relieved, c. structuredefining a station for receiving cassettes transferred from the X-raystation, including a pivotal wall for supporting cassettes transferredto the receiving station; and d. means to progressively pivot said wallas cassettes are transferred to the receiving station.
 2. A film changeras defined in claim 1 including a movable carriage at the receivingstation, means connecting the movable carriage and the pivoted wall somovement of the carriage controls pivoting of the wall, and a connectionbetween the film cassette supply and transfer mechanism and the carriageso that the carriage is moved as cassettes are transferred from andsupplied to the X-ray station.
 3. A film changer as defined in claim 2including another carriage, means to drive the said carriageindependently of the first carriage to pivot the wall and to move themeans supporting the film cassettes away from the X-ray station when thefilm changer is reloaded.
 4. In a method of feeding a series of filmcassettes to an X-ray station, and thence to a receiving station, thesteps comprising: a. applying a force to a plurality of cassettes tourge the plurality toward an X-ray station; b. exposing film in onecassette of the plurality to X-rays at the X-ray station while applyingsaid force; c. relieving the force urging the plurality of cassettestoward the X-ray station after the film has been exposed; d. while theforce is relieved removing the cassette with the exposed film from theX-ray station by initially pushing it from an initial position at theX-ray station in a generally vertical, downward, direction and thenengagiNg it and conveying it from the X-ray station to a receivingstation; e. applying another force to move the remaining cassettes ofthe stack toward the X-ray station; f. receiving the cassette in agenerally upright position and supporting it against an upright support;and g. progressively changing the angle at which the upright support isoriented as successive cassettes are received.
 5. A film changer for usein taking a series of radiographs, said film changer comprising: a.structure defining an X-ray station at which film cassettes are exposedto X-rays; b. means to supply cassettes to the X-ray station; c.transfer means to move exposed cassettes from the X-ray station; d. areceiving station for receiving exposed cassettes transferred from theX-ray station, said receiving station including a pivotally movable wallmember; and e. means to progressively change the angle of the wallmember as cassettes are transferred to the receiving station.
 6. A filmchanger as set forth in claim 5 wherein the means to progressivelychange the angle of the wall member as cassettes are transferred iscontrolled by the means to supply cassettes to the X-ray station.
 7. Afilm changer as set forth in claim 6 including first and second camplates extending from the wall member in planes that intersect thepivotal axis of the wall, first and second carriages movable relative tothe pivot axis, each along a plane of one of the cam plates, a first camfollower on the first carriage engageable with the first cam plate, asecond cam follower on the second carriage engageable with the secondplate, means to independently drive the said first carriage to move thefirst cam follower along the first cam to pivot the wall member from afirst position to a second position, a spring biasing said wall memberfrom said second position toward said first position, and meansassociated with the cassette supply means to control movement of saidsecond carriage and second cam follower progressively along the secondcam as cassettes are transferred from the X-ray station to the receivingstation to allow the wall member to return to the first position.
 8. Afilm changer as set forth in claim 7 including a movable shutter betweenthe X-ray station and the receiving station, and means actuated by thefirst carriage when it moves to tilt the wall member, to open theshutter and permit film cassettes to be transferred.
 9. A film changeras set forth in claim 6 including a movable carriage reciprocable tocontrol pivoting of the wall member.
 10. In a method of transferring aseries of film cassettes in a generally upright orientation from anX-ray station to a receiving station the steps comprising: a. moving aseries of cassettes one after the other from an upper location at anX-ray station to a lower location away from the X-ray station along apredetermined path; b. receiving the cassettes at the lower location ina generally upright position; c. maintaining the cassettes supportedgenerally upright with a pivoted wall oriented generally upright; and d.pivoting the wall from an initial inclined position to a position moretoward the vertical as cassettes are moved from the upper location tothe lower location.
 11. The method of claim 10 wherein the wall ispivoted each time a successive cassette is transferred to provide anenlarged zone in which to accommodate additional cassettes.